Help! Why is My Club Head Speed is Always Slow in Zepp App

As a golf beginner, I have purchased Zepp 2 golf swing analysis to help me practice my swing tempo and consistency. It really helped me to adjust my swings especially for the club plane and hand plane consistencies. However, my driver swing speed is always in the low 70 MPH range despite that I have tried super hard swings even with baseball swing styles. I bought a preowned Callaway Rogue Draw Driver with regular shaft from Callaway Preowned eBay store and started to doubt if my shaft was too soft. Even my irons swings were in the low 70 MPH mark with full power. I also began to doubt if I made the wrong decision to get the graphite shafts instead of iron ones. I have even tried different golf gloves, different tablets and researched numerous online videos and posts. However, I still struggle with slow driver club head speed even though I could hit 200 yards occasionally. Below is my regular practice swing screenshot.

I used to play baseball/softball and I could hit long balls. This was my swing with 100% power and I still got 72 MPH. This is truly disappointing. My SwingCaddie 2 launch monitor at least tells me that I could generate around 85 MPH swing speed. Why is Zepp app always showing subpar club speed?

Zepp’s website hasn’t been maintained for a while. Their FAQ page is pretty outdated. I guess this company went to a maintenance mode after I lost the lawsuit against Blast Motion. After several online researches, I found their old user manual and it has a paragraph that says the sensors uses club length needs to be set correctly. (http://www.zepp.com/assets/docs/user_guide_zepp_golf_3.0_Zepp1.pdf) I selected TaylorMade M4 iron set and Callaway Rogue 10.5 degree loft correctly. However, I did not pay attention to the club length!!

The club length setting can be found from Profile -> Clubs.