The easiest way for a beginner to migrate an OLM file to Office 365 is to transfer the OLM mailbox data directly to the Office 365 account through IMAP. This avoids first converting the OLM file into another format.
You’ll need the OLM file, Office 365 email address, password, and IMAP details. The basic process is to load the OLM file, select the required mailbox folders, enter the Office 365 IMAP credentials, and start the migration. Emails, attachments, and folder structure can then be transferred to the Office 365 mailbox.
For this type of migration, Softaken OLM to IMAP Migration is one option to consider because it is designed to move OLM mailbox data directly to an IMAP account.
For a beginner, I’d recommend migrating one small folder first and checking the emails and attachments in Office 365 before transferring the complete OLM file.