Show all jobs by company

The shortcodes don’t have a company arg you can use, but you could query using a get_posts function.

https://codex.www.ads-software.com/Template_Tags/get_posts

Company names by default are stored as post meta, so a meta_query could be used to query a specific company by name.

Alternatively you may want to see if https://www.ads-software.com/plugins/wp-job-manager-companies/ is suitable. I’ve not tested it personally.