Marko_jo wrote:
I’ve tried to contact them but because of the lockdown all kinds of stores and services are closed.
I might have access to another Mac, yes!
How does that work? Can you explain, please?
Sierra? Not clear from above if that was your preferred OS... Seems way back there.
I do know if you can run Sierra you can run High Sierra, but you said Big Sur.......?
Non-the-less—
You can download the older macOS —verify you are using the Safari browser to download/initiate the macOS links:
installer backups on this server:
https://support.apple.com/en-gb/HT211683
Create a bootable installer to use —How to create a bootable installer for macOS - Apple Support
Never pays to get too far behind in the hardware or software, it just makes the transition more difficult.
Baby steps along the way is easier than a giant leap.