yes Facebook didn't provide good document for this. I also struggled a lot. we can use time range to fetch the data for specific date or date range.
Inside Graph API you can provide like below
me?fields=id,name,adaccounts{campaigns{adsets{ads{insights.time_range({'since':'2020-05-01','until':'2020-05-01'}){adset_id,campaign_id,ad_id,clicks}}}}}
note the syntax from insights.time_range({'since':'2020-05-01','until':'2020-05-01'}).
once you provide above code and submit, fb provides the codes for different languages such as JavaScript, ios , android etc.
curl will looks like below
curl -i -X GET \
"https://graph.facebook.com/v6.0/me?fields=id%2Cname%2Cadaccounts%7Bcampaigns%7Badsets%7Bads%7Binsights.time_range(%7B'since'%3A'2020-05-01'%2C'until'%3A'2020-05-01'%7D)%7Badset_id%2Ccampaign_id%2Cad_id%2Cclicks%7D%7D%7D%7D%7D&access_token="