@kelzblogsIf you are trying to change an existing lot into a retail lot, you need to set the lot type to 'retail' via the manage worlds feature. Then you can use your sims phone to purchase a retail store - it should take you to Magnolia Prominade (the small world that came with Get to Work, with some existing retail stores for purcahse), but you can also navigate to any other worlds that you own and choose any lot that is set as a 'retail' lot.
https://www.carls-sims-4-guide.com/expansionpacks/gettowork/retail/When you say the cash register symbol, do you mean in the bottom right hand side user panel?