Rodman Public Library in Alliance, Ohio offers online music lessons from ArtistWorks, and included in those are lessons by classical mandolinist Caterina Lichtenberg. The link for all research databases on the RPL site is https://www.rodmanlibrary.com/databases.
The link for all ArtistWorks lessons is http://www.rbdigital.com/rodmanoh/service/artistworks.
The link for classical mandolin lessons is https://artistworks.com/caterina-lichtenberg-rb/learning.
Lichtengerg's lessons are divided into beginner, intermediate, and advanced, and each of those is divided into lessons addressing specifics, such as the down stroke, tremolo, etc.
You must have a Rodman library card or an ecard to use this resource, and you must register with ArtistWorks. Once you do that, click on "Get Started" and choose a course.
This is the link to the RPL ecard: https://www.rodmanlibrary.com/online.
I recommend perusing the RPL website for its wealth of online information. Click on https://www.rodmanlibrary.com/, then on "Find Information", then on "Research Databases".