When I try to install eXist 4 database, I get this error:

Caught an exception while initializing db: Wrong password for user [admin]
--- Initialization complete. Shutdown embedded database instance ---
org.xmldb.api.base.XMLDBException: Wrong password for user [admin]
at org.exist.xmldb.DatabaseImpl.getUser(DatabaseImpl.java:292)
at org.exist.xmldb.DatabaseImpl.getLocalCollection(DatabaseImpl.java:189)
at org.exist.xmldb.DatabaseImpl.getCollection(DatabaseImpl.java:167)
at org.exist.xmldb.DatabaseImpl.getCollection(DatabaseImpl.java:158)
at org.xmldb.api.DatabaseManager.getCollection(Unknown Source)
at org.exist.installer.Setup.initDb(Setup.java:77)
at org.exist.installer.Setup.main(Setup.java:66)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.exist.start.Main.invokeMain(Main.java:140)
at org.exist.start.Main.run(Main.java:453)
at org.exist.start.Main.main(Main.java:64)
Caused by: org.exist.security.AuthenticationException: Wrong password for user [admin]
at org.exist.security.internal.RealmImpl.authenticate(RealmImpl.java:274)
at org.exist.security.internal.SecurityManagerImpl.authenticate(SecurityManagerImpl.java:435)
at org.exist.xmldb.DatabaseImpl.getUser(DatabaseImpl.java:290)
... 13 more
[B@4c86da0corg.exist.security.AuthenticationException: Wrong password for user [admin]
at org.exist.security.internal.RealmImpl.authenticate(RealmImpl.java:274)
at org.exist.security.internal.SecurityManagerImpl.authenticate(SecurityManagerImpl.java:435)
at org.exist.xmldb.DatabaseImpl.getUser(DatabaseImpl.java:290)
at org.exist.xmldb.DatabaseImpl.getLocalCollection(DatabaseImpl.java:189)
at org.exist.xmldb.DatabaseImpl.getCollection(DatabaseImpl.java:167)
at org.exist.xmldb.DatabaseImpl.getCollection(DatabaseImpl.java:158)
at org.xmldb.api.DatabaseManager.getCollection(Unknown Source)
at org.exist.installer.Setup.initDb(Setup.java:77)
at org.exist.installer.Setup.main(Setup.java:66)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.exist.start.Main.invokeMain(Main.java:140)
at org.exist.start.Main.run(Main.java:453)
at org.exist.start.Main.main(Main.java:64)
Caused by: org.exist.security.AuthenticationException: Wrong password for user [admin]
at org.exist.security.internal.RealmImpl.authenticate(RealmImpl.java:274)
at org.exist.security.internal.SecurityManagerImpl.authenticate(SecurityManagerImpl.java:435)
at org.exist.xmldb.DatabaseImpl.getUser(DatabaseImpl.java:290)
at org.exist.xmldb.DatabaseImpl.getLocalCollection(DatabaseImpl.java:189)
at org.exist.xmldb.DatabaseImpl.getCollection(DatabaseImpl.java:167)
at org.exist.xmldb.DatabaseImpl.getCollection(DatabaseImpl.java:158)
at org.xmldb.api.DatabaseManager.getCollection(Unknown Source)
at org.exist.installer.Setup.initDb(Setup.java:77)
at org.exist.installer.Setup.main(Setup.java:66)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at org.exist.start.Main.invokeMain(Main.java:140)
at org.exist.start.Main.run(Main.java:453)
at org.exist.start.Main.main(Main.java:64)
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.exist.storage.BrokerPool (file:/home/ted/eXist-db/exist.jar) to field java.lang.Thread.threadLocals
WARNING: Please consider reporting this to the maintainers of org.exist.storage.BrokerPool
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

What is it and how do I fix it?

This is now a separate problem, if Java is now working on your system, so you may be best to start a new thread about the Exist 4 database. The main error it appears to report is a wrong password.

Include info on which tutorial you are using to install Exist 4 and the steps you took before obtaining the error.

I just started a new thread. I hope you can assist me further.