Fannie Mae has no limits on how many investment loans in a condo complex, they just have the below guidelines about a Single Entity owning a certain numbers/% of condos in a complex:Single-Entity OwnershipA project meets the definition of single-entity ownership when a single entity (the same individual, investor group, partnership, or corporation) owns more than the following total number of units in the project:projects with 5 to 20 units – 2 unitsprojects with 21 or more units – 20%

I partnered with a small group of investors, most of us who met here on BP, for the acquisition and financing (through Fannie Mae) of portfolio of six modern duplexes in Huntsville.

Keep in mind, properties in an LLC don't qualify for Fannie Mae loans. 

As my friend @Chris Mason showed me a while ago, Fannie Mae changed their guidelines and now allows you to finance in your personal name and afterward, move the loan into an LLC that the borrowers are the majority members of.

to give you an idea, the bank that i use in Indiana, their conventional side has 6 month seasoning period (this is a freddie mac/fannie mae requirement so all banks will have this seasoning period). 

Most banks sell there loans and so they have to write them to Fannie Mae standards... the good thing is that you can look up those standards real easy.  

Fannie Mae 

I’m thinking about maybe using Fannie Mae, FHA, Freddie Mac Loan to finance my next property (House-Hack).

A very direct one is the quasi government organizations like Fannie Mae and Freddie Mac.

If you are trying to get cheap government backed loans, then You'll need to deal with a Government Sponsored Entity (Fannie Mae, Freddie Mac, ... or FHA).