In terms of free of charge training there isn’t an awful lot on the market that provide official certification, but Microsoft have an incredible library off resources.
Microsoft 365 Training
From here you can select the app you want to learn and dig as deep as you like into that.
I would also recommend (and it’s how I do a lot of my learning) a few great You Tube channels. There are some brilliant ones on Excel which I assume will be the focus.
This video is highly recommended as it covers the main excel functions (eg. Round, VLookUp, If, Sums and so much more) that is relevant to accountants.
Excel for Accounting - 10 Excel Functions You NEED to KNOW! - YouTube
This is also a great channel too Kevin Stratvert - YouTube
Specifically relating to Microsoft 365 I would suggest asking the new team member to watch these…
This covers pretty much all the Apps in Microsoft 365 (most I assume you don’t use) but it is only 17 minutes long All the Microsoft 365 Apps Explained - YouTube
15 minute EXCEL tutorial Excel Tutorial in 15 min - YouTube
25 minute ONE DRIVE tutorial How to use Microsoft OneDrive - YouTube
20 minute tips and tricks on OUTLOOK Top 20 Microsoft Outlook Tips & Tricks - YouTube
20 minutes how to use SHAREPOINT How to use Microsoft SharePoint - YouTube
