I was told it takes 48 hours for the irs to approve a return in order to get a refund advance. It’s been 48 hours and I’ve heard nothing

That is when the IRS is accepting returns at a normal pace which will not happen until 1/27...right now they have only pulled a few returns for system testing...so until your return is pulled and accepted you must wait.  

https://www.irs.gov/newsroom/irs-opens-2020-filing-season-for-individual-filers-on-jan-27