Hi @Wille Schneider ,
You can convert your disk from GPT to MBR with either Diskpart or via the Disk Management, you can follow along here:
Convert a GPT disk into an MBR disk
https://learn.microsoft.com/en-us/windows-server/storage/disk-management/change-a-gpt-disk-into-an-mbr-disk
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Best regards,
Leon