  The IRDC SDC335.579-0.292 (SDC335) is a massive star-forming cloud found to
be globally collapsing towards one of the most massive star forming cores in
the Galaxy. SDC335 hosts three high-mass protostellar objects at early stages
of their evolution and archival ALMA Cycle 0 data indicate the presence of at
least one molecular outflow in the region. Observations of molecular outflows
from massive protostellar objects allow us to estimate the accretion rates of
the protostars as well as to assess the disruptive impact that stars have on
their natal clouds. The aim of this work is to identify and analyse the
properties of the protostellar-driven molecular outflows within SDC335 and use
these outflows to help refine the properties of the protostars. We imaged the
molecular outflows in SDC335 using new data from the ATCA of SiO and Class I
CH$_3$OH maser emission (~3 arcsec) alongside observations of four CO
transitions made with APEX and archival ALMA CO, $^{13}$CO (~1 arcsec), and HNC
data. We introduced a generalised argument to constrain outflow inclination
angles based on observed outflow properties. We used the properties of each
outflow to infer the accretion rates on the protostellar sources driving them
and to deduce the evolutionary characteristics of the sources. We identify
three molecular outflows in SDC335, one associated with each of the known
compact HII regions. The outflow properties show that the SDC335 protostars are
in the early stages (Class 0) of their evolution, with the potential to form
stars in excess of 50 M$_{\odot}$. The measured total accretion rate onto the
protostars is $1.4(\pm 0.1) \times 10^{-3}$M$_{\odot}$ yr$^{-1}$, comparable to
the total mass infall rate toward the cloud centre on parsec scales of 2.5$(\pm
1.0) \times 10^{-3}$M$_{\odot}$ yr$^{-1}$, suggesting a near-continuous flow of
material from cloud to core scales. [abridged].
