NetHunterStore apk gpg verification

Hi all,

I couldn't seem to verify the NetHunterStore.apk using gpg. I imported the official kali public key using 'wget -q https://archive.kali.org/archive-key.asc | gpg --import' (as instructed here: https://www.kali.org/downloads/) then got the apk; 'wget -q https://store.nethunter.com/NetHunterStore.apk' and the sig file; 'wget -q https://store.nethunter.com/NetHunterStore.apk.asc'. However, when I run 'gpg --verify NetHunterStore.apk.asc' I get the following:

"gpg: assuming signed data in 'NetHunterStore.apk'
gpg: Signature made Tue 06 Aug 2019 07:00:33 BST
gpg: using RSA key 04EFAC45BC67F8C2CB8ABFE0B124ED68AA07EFA9
gpg: issuer "[email protected]"
gpg: Can't check signature: No public key"

Am I missing something?