I created a collector app and shared all of the content (Feature, service definition, Web Map, Dashboard) with a group in ArcGIS Online. Then I sent out invitation to the group. My question is rather than sending out 20 different invitation to the group and having to manage all of those accounts. Can I create a single account (Username and password) and have multiple people out in the field use that account to collect data using the collector app. Would having multiple people collecting data simultaneously using the same account-affect the data quality and integrity. What is the best solution to this problem?
Yes, you can have multiple people signed into the same account in the field. There may be issues if two people are editing the same point at the same time, but this issue would be a problem whether those people were signed in using the same account or different accounts.
While it's technically possible for different users to sign in to our apps using the same Organizational Account it does go against the the license agreement. Each organizational accounts is intended to be used by one person.
There may however be some other options available to you.
Please contact me (David Cardella email@example.com) and I can get you in touch with the right person.