You're extracting those raw vfiles out of a complete dev package. Download the complete package from parent level and you may compile the .asl files with the provided makefile.
These .asl files are plain source code. You may rename the extension to .dsl to open them in MaciASL app. MaciASL uses .dsl extension for source code and .aml extension for compiled code. Here, the .asl files are meant to be compiled with the command line (Intel) iasl tool through the makefile. If you open up the makefile with a text editor, you'll see how it operates.
As for errors, well they can depend on the ACPI version the code is based on and the ACPI version the compiler will be using. Check your MaciASL settings here. After a few years with good old DSDTEditor, I switched to rehabman's version of MaciASL several years ago and have been using that same version without problems ever since. Of course, I had to get into ACPI coding to be able to fix DSDT/SSDT when compiler returns errors...
https://github.com/RehabMan/Intel-iasl
https://github.com/RehabMan/OS-X-MaciASL-patchmatic