I'm new to Linux, I've done a good job configuring the system and installing the necessary packages and drivers.

After installing the firmware-amd-graphics package from apt, I started getting ACPI related errors when I boot into Debian, the system is working well but I'd like to fix that error to avoid any misbehaviors.

That's a part of the dmesg report:

[ 11.013536] fbcon: radeondrmfb (fb0) is primary device
[ 11.208205] Console: switching to colour frame buffer device 240x67
[ 11.213240] radeon 0000:00:01.0: fb0: radeondrmfb frame buffer device
[ 11.242220] ACPI Error: [\_SB_.ALIB] Namespace lookup failure, AE_NOT_FOUND (20160831/psargs-359)
[ 11.242277] ACPI Error: Method parse/execution failed [\_SB.PCI0.VGA.ATC0] (Node ffff9878da4d0b68), AE_NOT_FOUND (20160831/psparse-543)
[ 11.242341] ACPI Error: Method parse/execution failed [\_SB.PCI0.VGA.ATCS] (Node ffff9878da4d0460), AE_NOT_FOUND (20160831/psparse-543)

OS details:

Linux debian 4.9.0-8-amd64 #1 SMP Debian 4.9.144-3.1 (2019-02-19) x86_64 GNU/Linux

GPU details:

00:01.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Kaveri [Radeon R7 Graphics] [1002:130f] (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Kaveri [Radeon R7 Graphics] [103c:2215]
Flags: bus master, fast devsel, latency 0, IRQ 46
Memory at e0000000 (64-bit, prefetchable) [size=128M]
Memory at e8000000 (64-bit, prefetchable) [size=8M]
I/O ports at f000 [size=256]
Memory at ff700000 (32-bit, non-prefetchable) [size=256K]
Expansion ROM at 000c0000 [disabled] [size=128K]
Capabilities: [48] Vendor Specific Information: Len=08 <?>
Capabilities: [50] Power Management version 3
Capabilities: [58] Express Root Complex Integrated Endpoint, MSI 00
Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>

Not sure if this will help or not.

Link