It's recommended to have proper vacuum pump at installation, but if it's not available, even fridge or AC compressor can vacuum reasonably well, as something is better nothing at all.
Another benefit of this procedure is "leak testing", because minor gas leaks lose gas very very slowly and cannot be detected instantly, and it can take months or even years to show symptoms of minor gas leak.
The people whose AC gas leaked after few months or even just a very few years later had their gas leaking extremely slowly slowly, since the beginning of installation.
None of my Split ACs ever developed even a minor leakage, because i vacuumed and leak tested with pressure at time of installation.
Some of them are 10+ years old non inverters (still no gas leaks, no gas top ups ever, still exceptional cooling) and some are 2-3 years old inverters.
All are Fujitsu General. Never had a single AC issue or cooling issue in my life, mainly because of proper installation.
