Can I fit Artificial Grass onto soil?

Will it be okay if I fit my grass onto soil?

I won't recommend you to install artificial grass directly onto the soil. You need to make sure have a sub base build for proper drainage and smooth/compacted surface to lay your turf. Soil surface won't give you good drainage capacity and it can become a problem if you live in a wet area with a lot of rains or if you have dogs to use your artificial grass lawn.
Typically, you will need to excavate about 4" of soil, and put drain rocks and finer product such as decomposed granite, compacted it to about 90% before you laying your turf.

You can find a full process of installing artificial grass at this link below:
https://megagrass.com/pages/installation

I thought I can just lay the artificial grass on the soil since our soil here is kinda solid. Seems like installing will require a hard work so I'll just contact an installer to help me out.

I will recommend you to use infills before installing artificial grass for better drainage.

Too much dirt and mess if you don’t use any sub-base like infills or fine rocks. Just mere soil will be prone to water stocking up and mud everywhere.

Yeah, drainage will be your problem. As time goes by, the soil will become mud because of your faulty drainage and that mud will not be steady anymore. So sub-base will be helpful.