I am using SharePoint 2013 (Office 365) . There are internal and external users to this site. While trying to give access to new external users (mostly aged ones) who don't have a Microsoft account, find it difficult to first create a MS account, then get the credentials to log in to my site. How can I help them avoid this? Or when adding a new external user , can I ask for their details there which helps it to automatically create the account and then just share the credentials with the user? TIA
You can't, that is the auth flow you have to work with. You either share externally and they have to use an existing O365 account or Microsoft account to log in, or you give them credentials in your domain and license them.
I think most would agree, letting Microsoft deal with the credentialing process of users not in your business is a much better trade off than managing user credentials and associated O365 license, not matter the slight inconvenience a first time user has to deal with.