Nek wrote

i cannot connect from my mobile i get message "connected, no internet"

Usually devices show the portal page automatically if they detect no connection to the Internet at a WLAN hotspot. Some older devices don't do so. In the latter case you need to start a web browser and type in an URL of a website you want to visit. The browser then will be redirected to the portal page where you can type in the voucher code.

Make sure to enable »HTTPS redirect« in OC200's Portal Page settings if you want to get redirected by typing an address starting with https://, else you need to type an address which starts with http://.