We can set up a report to run itself daily, weekly, or monthly and send the results automatically to the people who need to see them, so that we don’t have to remember to log in and do it.

Troubleshooting
1. Make sure the running user have access to the report folder. Else, the report won’t be sent.
2. Classic – https://help.salesforce.com/articleView?id=000321705&language=en_US&type=1&mode=1
3. Lightning – https://help.salesforce.com/articleView?id=reports_subscribe_lex.htm&type=5
4. Timezone is based on the user’s timezone who is scheduling it.
5. Check email log.
6. Check email deliverability if the emails are not sent.
7. Use Test Deliverability to check whether emails are receiving from Salesforce.
8. Results are based on the running the user’s permissions.
9. Max limit is 10 MB.