1. Please kindly help to provide details of how I can go about solving this problem. I signed in into my ArcGIS Online account with the hope of inviting members into my organization but the response was insufficient member. Attached below is the message displayed.
2. Also, I need help on how I can change my log in method. I activated my ArcGIS Online using social means through my email but when I want to sign in directly it wasn't accepting it. The question now is, how can my login type from social to ArcGIS.
Are you on a trial subscription for your organization? If so, you will be limited to 6 members, I think. Look under your Licenses tab, then click User Types. See if it says 0 available. You might have a different user type still available.
are you signing into arcgis.com or a specific organization website, like xxx.maps.arcgis.com?
It sounds like you have a free public account. You are using it for personal, noncommercial use. In this case, you can't invite other members. If you're interested in creating an organization for a team of members, consider trying a free trial here: https://www.esri.com/en-us/arcgis/products/arcgis-online/trial
I assume you bought it through here? https://www.esri.com/en-us/arcgis/products/arcgis-for-personal-use/buy
This is for personal use only. You can't create a team of members with your personal account.
The link I shared before was to create an organizational account, which would allow for a team of members.
With your personal account, you can share your data with the public, or keep it private. You cannot create a group of members to share it with. To do that, you'd need an organizational account.
If you're interested in creating an organization for a team of members, consider trying a free trial here: https://www.esri.com/en-us/arcgis/products/arcgis-online/trial
I don't know how to change your login type. I believe you should be able to sign in with your username and password without going through your social media. Did you create a username?