Condos are a group ownership property type and they're categorized by lenders as more risky than a typical SFR (single family residence). With a condo you typically don't own the land under the building and because lenders see them as a slightly higher risk, they underwrite the property more stringently. This also means you can expect slightly higher rates and down payments. There are many different condo categories and approval types.
To get started buying any condo you'll want to find out if it's "Fannie Mae or FHA approved". If it is, that's great and you'll be able to finance up to 97% of the price depending on location, your personal credit and other standard loan qualifying factors.
If it's not approved or able to be approved, there are options for that as well. Most options for a non-warrantable condo (not Fannie Approved) will require a larger down payment, usually starting around 20%.
The building HOA usually knows if the building is approved, but they may not. Regardless, the HOA or management company will have to complete a Fannie Mae property questionnaire. Some of the questions on the questionnaire pertain to owner occupancy rates, concentration of units owned by one entity, pending litigation, percentage of space used for commercial purposes, etc.
Here are links to Fannie and FHA see if your building is already approved, but even if it's not on these lists the building can be approved with a approved questionnaire and underwriting approval.
https://www.fanniemae.com/singlefamily/project-eligibility-review-service Fannie MAE