On an older MacBook, cannot even install Firefox and the version of Chrome which does install does not allow full functionality for Shopify. Perhaps an alternative browser would allow login and management for Shopify accounts?
Shopify requires an up-to-date web browser to make sure that you can use all of Shopify's admin features. Shopify currently supports the latest two versions of all browsers, unless otherwise noted.
Browsers supported by Shopify include:
Google Chrome Mozilla Firefox Apple Safari Microsoft Edge Opera Apple Safari for iOS Google Chrome for Android
... cannot even install Firefox...
If you can't for some reason install latest native MacOS version of Firefox, try installing Firefox for Windows, using Wine. Some apps appear work better as Windows versions in Wine than native ones in Linux – the same could happen with MacOS.