I have iOS 13 but I did set this up before I updated my phone so I'm not sure if I was just grandfathered in. Try the following in the Health app:

1. Hit the icon in the top right corner to go to your account.
2. Under the privacy section hit apps.
3. You should see Pokemon GO there.

Then just allow access to everything as suggested in the instructions from Pokemon GO.

I have iOS 13 but I did set this up before I updated my phone so I'm not sure if I was just grandfathered in. Try the following in the Health app:

1. Hit the icon in the top right corner to go to your account.
2. Under the privacy section hit apps.
3. You should see Pokemon GO there.

Then just allow access to everything as suggested in the instructions from Pokemon GO.

EDIT:

Per the conversation in the comments, follow the directions in this Reddit thread https://www.reddit.com/r/pokemongo/comments/c58uo5/adventure_sync_on_ios_13_possible/ to fix this issue in iOS13 if the above did not work:

1. Turn off automatic app download under General in the watch app (if you have an apple watch).
2. Reinstall Pokemon GO.

I have iOS 13 but I did set this up before I updated my phone so I'm not sure if I was just grandfathered in. Try the following in the Health app:

1. Hit the icon in the top right corner to go to your account.
2. Under the privacy section hit apps.
3. You should see Pokemon GO there.

Then just allow access to everything as suggested in the instructions from Pokemon GO.

I have iOS 13 but I did set this up before I updated my phone so I'm not sure if I was just grandfathered in. Try the following in the Health app:

1. Hit the icon in the top right corner to go to your account.
2. Under the privacy section hit apps.
3. You should see Pokemon GO there.

Then just allow access to everything as suggested in the instructions from Pokemon GO.