Hello, if you want to join a group by yourself, the group admin must turn on the "Group can be searched" in the "Group Settings" > "Group Management", and find the group in the following methods:
1. By group QR code: Press the "+" at the DingTalk mobile "Messages" right upper corner, select "Scan QR Code" and to add the group by scan.
2. By group number: The group can be found at the "Group Settings" page, just under the group name. And users can go to the "+" at "Messages" and select "Add Contacts" to search the group by the number.
3. By the group name: Users can input group name at the search bar to find the group and apply directly.
If the group admin doesn't turn on the "Group can be searched" function, we suggest you contact the group admin to add you into the group.
Guess you want to learn more about: How to add group members？