You were admitted to the university as a whole. You actually applied to the whole university with a preference for a specific school/college. Easy to change school/college. CALS is the college of Agriculture and Life sciences, btw- L&S is Letters and Sciences. Most students are in L&S and most freshmen as well until they get admitted to another one such as engineering, education, nursing, business, etc. There are a few direct admits currently to engineering and business. Most need to apply based on their UW record. Most freshmen will have mainly L&S courses.
Your admission to UW did NOT depend on your proposed major, if any. All students need to be admitted to their major, based on the college record. Easy to do, typically if you want the major you will meet requirements- such as the gpa requirement. Some majors are limited because of the resources available- they can be competitive but once admitted you know you will be able to get the needed classes in a timely fashion (the reason for limits is to be sure students can be accommodated). For example, those wishing a teaching degree will be able to get their student teaching once admitted to that program. Likewise a few engineering majors are competitive to be sure those in the major get their classes. The steps to take for individual majors is delineated in their online departmental information.
Don’t worry. Specifying a major now is useful for SOAR advisor assignments. As a transfer student you can still make changes and will have advising.