The Online Power Profiler does not support Channel Sounding so can't really be used to estimate the power consumption. The recommended way to deal with this today is to get a Power Profiler Kit II, nrf-ppk2, and measure the current while running. There is a lot of flexibility in the BT CS spec so you can tweak it a lot and get very different power consumption numbers with trading of aquisition speed and accuracy.
using multiple antennas will most likely improve the reliability for indoor measurements. The Bluetooth stack in nRF Connect SDK 3.0.1 (the version you should be using now as it is Bluetooth certified :-) ) does support multiple antenna paths but the algorithms in the SDK does not so you will have to spin your own to test this.
In 2.9.0 the Channel Sounding support was experimental and under development with features missing/not compliant. With the 3.0.1 we had improved the SW maturity to be out of experimental and now Blueteooth qualified with the CS feature.
The error you're seeing seems to be due to you already having a folder with that name in your project. Please check in the file explorer whether v3.0.1 is there already.
It seems in the left hand side of your toolbar that you have an outdated toolchain. Please also try updating the Toolchain to v3.0.1. This can be done by pressing the "manage toolchains" and install v3.0.1 as well.
