Firefox keeps automatically updating, even when I've clicked in settings to check with me before updating
A piece of software I need to use for work requires an older version of Firefox (Firefox 68.4.2 ESR) to run, so in the past, I've had to delete Firefox and re-download the older version which has worked fine. However, I recently got a new Mac and now when I try the same thing it's not working. Whenever I first open Firefox after downloading it, it opens as the correct (older) version, however it does not seem to be able to connect to the internet and I get the spinning wheel that never ends, and then whenever I close out of Firefox and reopen it, it automatically updates to the newest version. I have multiple times gone into the settings on Firefox and changed my preferences to check with me before installing updates and I've gone into the settings of the App Store to make sure it's not automatically updating any apps or programs. My computer is currently running OS version 11.1 (Big Sur) and I'm wondering if maybe this version is too new to be compatible with Firefox 68 ESR? Any help, ideas, or advice is greatly appreciated!