macOS 10.4 (Mojave) was released 2 years ago. The computer you’re using is 9 years old. You received 7 years of new operating systems for that machine!
If you want to run modern operating systems and software, you should use a modern computer. You don’t have to buy a new, either.
I just purchased a used 2015 MacBook Pro for US$975. It is compatible with the current macOS 10.15 (Catalina), as well as the next version (11, aka Big Sur). I expect to use it for many, many years.
(For the record, I use WaveLab Pro 10.0 on both Windows 10 and macOS 10.14.)