Unable to change solc version using by dapp

[Maham]

Hi. I am using ubuntu 21 LTS version and trying to compile and run pickle.finance contracts using dapp.tools. The steps are mentioned here https://github.com/pickle-finance/protocol. I followed till the command dapp build upon which it gave me different compiler version error. But that was because dapp was using solc version 0.8.6 whereas the contracts needed to be compiled which version 0.6. I used these two commands:

dapp --use solc:0.6.0 build
nix-env -f https://github.com/dapphub/dapptools/archive/master.tar.gz -iA solc-static-versions.solc_0_6_0

to try to make dapp use verion 6 but after running dapp -version it still gives the following output

dapp 0.35.0

solc, the solidity compiler commandline interface

Version: 0.8.6+commit.11564f7e.Linux.g++

hevm 0.49.0

I need help on how to make it use version 6. Attaching screenshot of some of the errors:

[dxo]

You are using 0.6.0 on a contract that needs 0.6.7.