CSV export of Discovery results is available on Pro subscription plan only.
The number of CSV exports depends on the type of your subscription plan.
On monthly plans you can make:
60 CSV exports per month on Pro Instagram
60 CSV exports per month on Pro YouTube
90 CSV exports per month on Pro IG + YouTube.
On annual plans you can make unlimited CSV exports.
Additionally, please note that all plans have a technical limit on max 5.000 monthly exports per user. This limit can't be reached by human and is made to protect our data from scrapping.