'Acquire' is most commonly associated with a legal process/purchase, like acquiring property, acquiring a business, acquiring stock, etc. It is also commonly used in regard to 'acquiring skills,' like a language, a programming language, management skills, learning to read, etc.
Obtain is very general, usually reserved for acquiring physical things or access to something, but not always.
'Get' is the most basic way to express any of these things...something coming into your possession, whether physical, an abstract skill, access, a business, etc.