The website links to the cryptomator 2 app in the app store. Is this cryptomator 2 application secure?
Yes, both are made by Skymatic, the company that has developed cryptomator.
Cryptomator 2 for iOS is the newer version and complete open source. And it has a free trial mode, which the first app did not offer. The first version is only still available for the people who bought it as this app is needed to upgrade to the full version of Cryptomator 2 for free.
If you are new to Cryptomator and want to try the iOS app, please use Cryptomator 2. You do not need to buy the Cryptomator (1) iOS app