So i'm assuming you have trouble logging into simplicity. Maybe it's not letting you login like you normal do?, or it's not even going through the loading screen and it just shows a straight black screen? or it could be fetching updates get to 14/21 and say error fetching updates?
Simple solution is to clear out your cache. Usually with google chrome and firefox there are much simpler steps by just going into your browser settings. However some people may not know how to do it exactly on safari.
Open up your safari then click the dropdown for safari on your top bar (left side) near the apple symbol. Click on Preferences -> Click on Privacy -> Click on Manage website data -> (it will take some time but will load the website data for all your websites) scroll down till you see (Simplicityps.org) select it -> then click remove. From there all you need to do is go to simplicityps.org and redownload the client. It should redownload the cache and you'll be able to login.
If you have any issues with the above steps or just need further guidance feel free to comment! or Talk to me in-game!