Advice for Stockholm metro and buses for a large family

I'm researching the best way to get around Stockholm with my family. We are:

• 2 seniors
• 2 adults
• 5 kids ages 9 and under.

We arrived at the central train station last night and took the metro to get to our Airbnb. We bought individual tickets on the machines which was pretty time consuming for that many people. After we bought the single use paper tickets we couldn't figure out how to get through the barriers as there was nothing to scan on them. I was a little surprised at the cost of single use tickets after having used the trams and busses last week in Oslo.

1. Is there a way to purchase multiple tickets at a time?
2. Do single use tickets have the ability to open up the barriers at the metro?

I also tried the iOS mobile app but it won't accept my US Credit Card.

I read everything on the SL site at https://sl.se/en/fares–tickets/ and related pages.

We also researched the Stockholm pass. It's quite expensive compared to the Copenhagen pass that we purchased a few weeks ago as children and travel are not included. With young kids I'm not sure we could move quickly enough and visit enough attractions each day to make it worthwhile. It allows you to buy the Travel Card, which seems very convenient. But it looks like you can't purchase the Travel Card separately, so that's not an option unless we splurge for the full Stockholm pass.

Sorry for the rambling post; just trying to figure out if I missed anything. Given the above considerations, are single use tickets purchased at the machines in the metro our best option? Thank you!