I think you can only get tickets for games at Siebert through gophersports.com. You can either just buy them at U.S. Bank Stadium ticket office for those games or through or ticketmaster.
Here is what was in the single game tickets available article on Gopher Sports.
MINNEAPOLIS – Single game tickets for the 2020 Minnesota Baseball season are now on sale for all 31 home games scheduled to take place in Minneapolis this spring.
For the Gophers' 17-game slate at Siebert Field, tickets can be purchased through the
GopherSports website. Tickets cost $5 for seniors and youth (under the age of 18), as well as for groups of 15 people or more. General admission adult tickets are $8, with reserved chairback seats being $12.
As for Minnesota's 14-game schedule at U.S. Bank Stadium spanning from Feb. 22-March 11, tickets are available for $10 each through the U.S. Bank Stadium Ticket Office and
Ticketmaster. Minnesota highly encourages fans to purchase tickets at the U.S. Bank Stadium Ticket Office on game day to avoid online fees.
Daily tickets for all-day access to the
2020 CambriaCollegeClassic at U.S. Bank are also $10 per day. Full tournament packages are available for $25.
New to this year, season ticket holders receive free admission to all home games scheduled to be held at U.S. Bank Stadium in 2020. Students may also attend all U.S. Bank games free of charge in addition to all home games at Siebert Field.