Provided the heaters that you are using are certified portable construction heaters, with the hoses and regulators that attach directly to an individual portable propane cylinder, you do not have to be a gas fitter to connect or use the units.
The manufacturer’s installation instructions outline the clearances from the heater to combustible material, and from the heater to the propane cylinder which must be complied with. If the units have been altered, or are being connected in a way other than what is stipulated in the instructions, a gas fitter is required to perform the installation under an appropriate permit. As well, if the units are being connected to a venting system they would require a gas fitter to perform the installation under a permit.
If the units are rental units there are regulatory requirements of the rental company to instruct the users in the installation, use, and care of the units and the propane cylinders.
Important: A person must not use a portable heater for temporary heating unless the heater bears a current Technical Safety BC temporary heater decal, valid for two years, and applied by a gas fitter certifying as to its safety and operation.