Group messages are sent to individual contacts and must be downloaded

[AC Question]

After I push download then I can see them in the group text

 

[hallux]

Group texts are handled as MMS. There is often a setting in your texting app that you change to either automatically download MMS messages or prompt you to download MMS messages. Prompt is more secure (or WAS in the days of Stagefright) and is likely the setting you have selected.

Not knowing what app you're using, we can't easily explain the process to make the change.