How to prepare for University Applied Mathematics

I am a currently doing pre-study on Khan Academy and have been doing Algebra Basics but after (3) weeks I am not even through the first Unit (Foundations).. Which is causing stress as I start my second year University in Janurary 2025. I will be taking some classes I previously failed (Calc I, Micro, Stats) then continuing onto 2nd year (Calc 2, Linear Alg 2) etc.. I am starting to think I am doing the wrong lesson and should switch to Pre-Calc or even just starting the AP College Calculus AB for example. I am a mature student whos been out of school for 10+ years before going back to University in 22/23' and greatly struggled with Algebra in my first year of University and wanted to refresh it. Has anyone come accross a simliar situation and what do you suggest would be the most effective time constraint way to refresh. thank you. 
-C.