external hard drive issues

Hello everyone, I have been a simmer for some years now only on mac and about two years ago I recieved a Lenovo for Christmas. This is what I have been using to play, but as of recently my game has begun to be real laggy and slow. So, i got an external hard drive. I watched a video on youtube on how to transfer everything properly into this drive. I open my EA app to redownload my sims and add on content and it was stuck at preparing to install 2% for like 3 hours. I reset my EA and reset my computer and since it has continued to give me an error saying something went wrong pop up. I just wanted to play my game with less lag and get back into it. If anyone can provide me with any tip's videos or advice, I will be greatly appreciative of it. Also, my internet speed is at 830 mb per second so speed isn't an issue as well.