Your solicitor should have ensured that you are registered s a member of the management company. In my case, it was just a matter of days after I moved in.
"Subscription" refers to any charges the management company may decide on. It is worded in such a way as to overcome any new charges that the management company has to pass on to the owners. Thus, it could include, where applicable, such items as management service fees, water charges, refuse charges and any other charges not included in the management fees etc.
If you have bought a brand new apartment, it may be that the builder is still the main shareholder in the management company. If you bought a previously owned apartment than you are a member of the management company but if any charges subscriptions are outstanding then your right to vote is denied.