Register yourself with a foreign telephone number
We are indeed (only) a Dutch portal, which is why a foreign telephone numbers does not work for the two-factor authentication.
My advice is to perhaps register yourself with a fellow student or roommate's Dutch telephone number - for now. After you have logged in on your own computer, you do not always have to verify your account with the code via SMS (as long as you do not delete your internet history).
Hopefully this will provide more clarity. We are working behind the scenes on another solution for this, stay tuned.
Connect iPhone (Apple Health) without Selfcare app 
Unfortunately, the Selfcare app is not available in every foreign app store for example for connecting the iPhone. The best solution is then: download the Google Fit app for iPhone.
You can then easily link the Google Fit account to Selfcare:
Step 1. Open the Google Fit-app (
) and create an account.
Step 2. Under the settings at Google Fit you can indicate that you want to use activity tracking > track activities with Health.
Step 3. Log on to Selfcare and choose "meting toevoegen".
Step 4. Select the shoe from stappen (
) and click on “Koppel een wearable, smartphone of gezondheidsapp”.
Step 5. Select ‘Android: Google Fit’ and sign in with your credentials account of Google.
It's all a bit inconvenient, but we hope you can participate in the challenge this way!